This invention relates to the control of an air conditioning system. More particularly, this invention relates to the control of an expansion valve within an air conditioning system.
Air conditioning systems often have a plurality of compressor stages that can be individually activated or deactivated in response to the demand for cooling. These stages are typically activated or deactivated by a control program residing in a microprocessor dedicated to the control of the air conditioning system.
It has been found that a relatively high refrigerant flow condition will temporarily occur within the air conditioning system when the control program deactivates one or more compressor stages. This flow condition is typically corrected by throttling the expansion valve within the air conditioning system so as to thereby adjust the flow rate of the refrigerant within the system. This throttling action however usually occurs in response to the one or more stages having already been deactivated. In this regard, a typical expansion valve moves in response to a change in value of the superheat. It is to be noted that in extreme circumstances, the expansion valve may not react quickly enough and the superheat may drop low enough that liquid might enter the cylinders of the compressor. This may ultimately lower the life of the compressor.